The present disclosure relates to devices and methods for verifying compatibility between cooperating parts of a joint prosthesis.
Joint prostheses, such as artificial hip joints, comprise two cooperating parts that, in the implanted state, articulate with respect to each other. In an artificial hip joint, an acetabular shell and a femoral head, which is fixed to a femoral stem, articulate with respect to each other. In other words, during articulation, the stem cooperates with the shell via the head. As described herein, when referring to an artificial hip joint, the shell and the corresponding femoral head can be regarded as a first one of the cooperating parts, while the stem can be regarded as a second one of the cooperating parts.
Usually, manufacturers of joint prostheses provide their customers with a complete prostheses, i.e., with both cooperating parts. Before this background, there has been no need for a surgeon to verify whether the two cooperating parts are actually compatible with each other. Specifically, the surgeon can be sure that the two parts fulfill all relevant requirements for the articulation, which is to be provided by the two parts in the implanted state.
In hip replacement surgery, for example, it is known for the skilled person that the so-called range of motion (“ROM”) is an important articulation parameter. Artificial hip joints have to meet minimum ROM requirements, which are, for example, defined by an international standard (e.g., ISO 21535). These requirements comprise minimum articulation angles in specific planes, for example the anterior/posterior plane (“A/P plane”) and the medial/lateral plane (“M/L plane”), as further explained below.
As mentioned above, for a joint prosthesis that is provided completely from one single manufacturer, there is no need for the surgeon to verify whether or not the two articulating or cooperating parts of the prosthesis actually meet these ROM requirements since the manufacturer guarantees that this is the case.
However, when the first part of a joint prosthesis is provided by a first manufacturer and the second part of the prosthesis is provided by a second, different manufacturer, the surgeon has to make sure that these two parts are compatible with each other with regard to all relevant parameters, specifically with regard to one or more articulation parameters such as minimum articulation angles for the ROM.
In hip replacement surgery, for example, the minimum ROM requirements require a verification of the compatibility in both the A/P plane and the M/L plane. As known to the skilled person, the A/P plane is perpendicular to an A/P axis extending in anterior-posterior direction, while the M/L plane is a plane perpendicular to an M/L axis extending in medial/lateral direction.
Generally, all anatomical terms as mentioned in the present disclosure and relating to directions or locations, such as anterior, posterior, medial, lateral, proximal and distal, refer to an implanted state of the respective parts and implants described herein.